/****************************************************************************
 *
 * Copyright 2016 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/
/****************************************************************************
 * libc/time/lib_strftime.c
 *
 *   Copyright (C) 2009, 2011, 2013 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <tinyara/config.h>
#include <sys/types.h>

#include <stdio.h>
#include <time.h>
#include <debug.h>

#include <tinyara/time.h>

/****************************************************************************
 * Definitions
 ****************************************************************************/

/****************************************************************************
 * Private Type Declarations
 ****************************************************************************/

/****************************************************************************
 * Private Function Prototypes
 ****************************************************************************/

/****************************************************************************
 * Public Constant Data
 ****************************************************************************/

/****************************************************************************
 * Public Data
 ****************************************************************************/

/****************************************************************************
 * Private Data
 ****************************************************************************/
#if defined(CONFIG_LIBC_LOCALTIME) || defined(CONFIG_TIME_EXTENDED)
static const char *const g_abbrev_wdayname[7] = {
	"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
};

static const char *const g_wdayname[7] = {
	"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"
};
#endif

static const char *const g_abbrevmonthname[12] = {
	"Jan", "Feb", "Mar", "Apr", "May", "Jun",
	"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};

static const char *const g_monthname[12] = {
	"January", "February", "March", "April", "May", "June",
	"July", "August", "September", "October", "November", "December"
};

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Function:  strftime
 *
 * Description:
 *   The  strftime()  function  formats the broken-down time tm according to
 *   the format specification format and places the result in the  character
 *   array s of size max.
 *
 *   Ordinary characters placed in the format string are copied to s without
 *   conversion.  Conversion specifications are introduced by a '%'  charac-
 *   ter,  and  terminated  by  a  conversion  specifier  character, and are
 *   replaced in s as follows:
 *
 *   %b     The abbreviated month name according to the current locale.
 *   %B     The full month name according to the current locale.
 *   %C     The century number (year/100) as a 2-digit integer. (SU)
 *   %d     The day of the month as a decimal number (range 01 to 31).
 *   %e     Like %d, the day of the month as a decimal number, but a leading
 *          zero is replaced by a space.
 *   %h     Equivalent to %b.  (SU)
 *   %H     The hour as a decimal number using a 24-hour clock (range 00 to 23).
 *   %I     The  hour as a decimal number using a 12-hour clock (range 01 to 12).
 *   %j     The day of the year as a decimal number (range 001 to 366).
 *   %k     The hour (24-hour clock) as a decimal number (range  0  to  23);
 *          single digits are preceded by a blank.  (See also %H.)  (TZ)
 *   %l     The  hour  (12-hour  clock) as a decimal number (range 1 to 12);
 *          single digits are preceded by a blank.  (See also %I.)  (TZ)
 *   %m     The month as a decimal number (range 01 to 12).
 *   %M     The minute as a decimal number (range 00 to 59).
 *   %n     A newline character. (SU)
 *   %p     Either "AM" or "PM" according to the given time  value, or the
 *          corresponding  strings  for the current locale.  Noon is treated
 *          as "PM" and midnight as "AM".
 *   %P     Like %p but in lowercase: "am" or "pm" or a corresponding string
 *          for the current locale. (GNU)
 *   %s     The number of seconds since the Epoch, that is, since 1970-01-01
 *          00:00:00 UTC. (TZ)
 *   %S     The second as a decimal number (range 00 to 60).  (The range is
 *          up to 60 to allow for occasional leap seconds.)
 *   %t     A tab character. (SU)
 *   %y     The year as a decimal number without a century (range 00 to 99).
 *   %Y     The year as a decimal number including the century.
 *   %%     A literal '%' character.
 *
 * Returned Value:
 *   The strftime() function returns the number of characters placed in  the
 *   array s, not including the terminating null byte, provided the string,
 *   including the terminating null byte, fits.  Otherwise,  it returns 0,
 *   and the contents of the array is undefined.
 *
 ****************************************************************************/

size_t strftime(FAR char *s, size_t max, FAR const char *format, FAR const struct tm *tm)
{
	FAR const char *str;
	FAR char *dest = s;
	int chleft = max;
	int value;
	int len;

	while (*format && chleft > 0) {
		/* Just copy regular characters */

		if (*format != '%') {
			*dest++ = *format++;
			chleft--;
			continue;
		}

		/* Handle the format character */

		format++;
		len = 0;

		switch (*format++) {
#if defined(CONFIG_LIBC_LOCALTIME) || defined(CONFIG_TIME_EXTENDED)
		/* %a: A three-letter abbreviation for the day of the week. */

		case 'a': {
			if (tm->tm_wday < 7) {
				str = g_abbrev_wdayname[tm->tm_wday];
				len = snprintf(dest, chleft, "%s", str);
			}
		}
		break;

		/* %A: The full name for the day of the week. */
		case 'A': {
			if (tm->tm_wday < 7) {
				str = g_wdayname[tm->tm_wday];
				len = snprintf(dest, chleft, "%s", str);
			}
		}
		break;
#else
		/* %a: A three-letter abbreviation for the day of the week. */
		/* %A: The full name for the day of the week. */

		case 'a':
		case 'A': {
			len = snprintf(dest, chleft, "Day");	/* Not supported */
		}
		break;
#endif
		/* %h: Equivalent to %b */

		case 'h':

		/* %b: The abbreviated month name according to the current locale. */

		case 'b': {
			if (tm->tm_mon < 12) {
				str = g_abbrevmonthname[tm->tm_mon];
				len = snprintf(dest, chleft, "%s", str);
			}
		}
		break;

		/* %B: The full month name according to the current locale. */

		case 'B': {
			if (tm->tm_mon < 12) {
				str = g_monthname[tm->tm_mon];
				len = snprintf(dest, chleft, "%s", str);
			}
		}
		break;

		/* %y: The year as a decimal number without a century (range 00 to 99). */

		case 'y':

		/* %C: The century number (year/100) as a 2-digit integer. */

		case 'C': {
			len = snprintf(dest, chleft, "%02d", tm->tm_year % 100);
		}
		break;

		/* %d: The day of the month as a decimal number (range 01 to 31). */

		case 'd': {
			len = snprintf(dest, chleft, "%02d", tm->tm_mday);
		}
		break;

		/* %e: Like %d, the day of the month as a decimal number, but a leading
		 * zero is replaced by a space.
		 */

		case 'e': {
			len = snprintf(dest, chleft, "%2d", tm->tm_mday);
		}
		break;

		/* %H: The hour as a decimal number using a 24-hour clock (range 00  to 23). */

		case 'H': {
			len = snprintf(dest, chleft, "%02d", tm->tm_hour);
		}
		break;

		/* %I: The  hour as a decimal number using a 12-hour clock (range 01 to 12). */

		case 'I': {
			len = snprintf(dest, chleft, "%02d", tm->tm_hour % 12);
		}
		break;

		/* %j: The day of the year as a decimal number (range 001 to 366). */

		case 'j': {
			if (tm->tm_mon < 12) {
				value = clock_daysbeforemonth(tm->tm_mon, clock_isleapyear(tm->tm_year)) + tm->tm_mday;
				len = snprintf(dest, chleft, "%03d", value);
			}
		}
		break;

		/* %k: The hour (24-hour clock) as a decimal number (range  0  to  23);
		 * single digits are preceded by a blank.
		 */

		case 'k': {
			len = snprintf(dest, chleft, "%2d", tm->tm_hour);
		}
		break;

		/* %l: The  hour  (12-hour  clock) as a decimal number (range 1 to 12);
		 * single digits are preceded by a blank.
		 */

		case 'l': {
			len = snprintf(dest, chleft, "%2d", tm->tm_hour % 12);
		}
		break;

		/* %m: The month as a decimal number (range 01 to 12). */

		case 'm': {
			len = snprintf(dest, chleft, "%02d", tm->tm_mon + 1);
		}
		break;

		/* %M: The minute as a decimal number (range 00 to 59). */

		case 'M': {
			len = snprintf(dest, chleft, "%02d", tm->tm_min);
		}
		break;

		/* %n: A newline character. */

		case 'n': {
			*dest = '\n';
			len = 1;
		}
		break;

		/* %p: Either "AM" or "PM" according to the given time  value. */

		case 'p': {
			if (tm->tm_hour >= 12) {
				str = "PM";
			} else {
				str = "AM";
			}
			len = snprintf(dest, chleft, "%s", str);
		}
		break;

		/* %P: Like %p but in lowercase: "am" or "pm" */

		case 'P': {
			if (tm->tm_hour >= 12) {
				str = "pm";
			} else {
				str = "am";
			}
			len = snprintf(dest, chleft, "%s", str);
		}
		break;

		/* %s: The number of seconds since the Epoch, that is, since 1970-01-01
		 * 00:00:00 UTC.  Hmmm... mktime argume is not 'const'.
		 */

		case 's': {
			len = snprintf(dest, chleft, "%d", mktime((FAR struct tm *)tm));
		}
		break;

		/* %S: The second as a decimal number (range 00 to 60).  (The range  is
		 * up to 60 to allow for occasional leap seconds.)
		 */

		case 'S': {
			len = snprintf(dest, chleft, "%02d", tm->tm_sec);
		}
		break;

		/* %t: A tab character. */

		case 't': {
			*dest = '\t';
			len = 1;
		}
		break;

		/* %Y: The year as a decimal number including the century. */

		case 'Y': {
			len = snprintf(dest, chleft, "%04d", tm->tm_year + 1900);
		}
		break;

		/* %%:  A literal '%' character. */

		case '%': {
			*dest = '%';
			len = 1;
		}
		break;
		}

		/* Update counts and pointers */

		dest += len;
		chleft -= len;
	}

	/* We get here because either we have reached the end of the format string
	 * or because there is no more space in the user-provided buffer and the
	 * resulting string has been truncated.
	 *
	 * Is there space remaining in the user-provided buffer for the NUL
	 * terminator?
	 */

	if (chleft > 0) {
		/* Yes, append terminating NUL byte */

		*dest = '\0';

		/* And return the number of bytes in the resulting string (excluding
		 * the NUL terminator).
		 */

		return max - chleft;
	}

	/* The string was truncated and/or not properly terminated.  Return
	 * zero.
	 */

	return 0;
}
